Protective garments, e.g., garments used by emergency workers, are generally made of fabrics that protect the wearer from the conditions the wearer expects to encounter, e.g., heat and flame in the case of firefighting garments. The fabrics used in such garments are typically waterproof and allow water vapor to pass from inside to outside the garment to provide comfort to the wearer during periods of exertion. An example of a waterproof breathable laminate produced from an expanded polytetrafluoroethylene (“ePTFE”) membrane is disclosed in U.S. Pat. No. 4,194,041. In this structure, the pores of the ePTFE are protected by a hydrophilic polyurethane layer, to prevent the pores of the ePTFE from becoming contaminated by lower surface energy liquids. Lower surface energy liquids tend to wet out untreated microporous structures, thereby reducing the hydrostatic resistance of the membrane and corresponding laminate structure.
Fabrics for protective garments may include a textile layer and a layer of a protective film that provides waterproofing. The protective film may be, for example, a treated micro-porous film, e.g., a film such as ePTFE as described in U.S. Pat. No. 4,194,041 above that has pores sized to permit vapor molecules to pass, while blocking water molecules, but has its surface energy modified to reduce its ability to wet out. Alternatively, the protective film could be a monolithic layer produced from a hydrophilic material such as polyurethane, nylon, or polyether block amides such as the polymer sold by Arkema under the trademark PEBAX®.
In many applications, it is necessary that the fabric be highly chemically resistant. For example, the Standard on Protective Ensemble for Structural Fire Fighting published by the National Fire Protection Agency (NFPA 1971, 2000 Edition) require the moisture barrier layer of fire fighting garments to resist penetration by a list of chemicals in accordance with ASTM F903 (Standard Test Method for Resistance of Protective Clothing Materials to Penetration by Liquids). Other applications, such as military applications and hazardous waste clean-up, also require high chemical resistance, but known laminates may not allow for effective transport of moisture, leading to heat stress.
It is important that fabrics used in protective garments be capable of withstanding laundering without loss of chemical resistance or, if laminated to a textile, to have resistance to de-lamination of the protective film from the textile.